CIDR prefix
/3
224.0.0.0
536,870,910 usable hosts · 536,870,912 addresses
The mask for /3 is 224.0.0.0 — 536,870,912 addresses, 536,870,910 usable hosts. Huge blocks used only by registries and carriers.
Mask
224.0.0.0
Wildcard
31.255.255.255
Addresses
536,870,912
Hosts
536,870,910
Worked example: 10.0.0.0/3
Network address0.0.0.0/3
Broadcast address31.255.255.255
First host0.0.0.1
Last host31.255.255.254
FAQ — /3
What is the subnet mask for /3?
The subnet mask for /3 is 224.0.0.0 (wildcard: 31.255.255.255). The first 3 bits are the network part, the remaining 29 are the host part.
How many hosts fit in a /3?
A /3 block holds 536,870,912 addresses, of which 536,870,910 are usable hosts (the network and broadcast addresses are excluded).
What is a /3 used for?
Huge blocks used only by registries and carriers.